This paper derived the formulation for the real efficient emission coefficient of secondary electron under the condition that high energy primary electron incident on metal obliquely.

推导出高能原电子斜入射时的金属的有效真二次电子发射系数的表达式，它与入射角的余弦近似成反比。

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Renewables account for only a small share of global primary energy consumption, which is still dominated by fossil fuels—30% each for coal and oil, 25% for natural gas.

可再生能源只占全球主要能源消耗的一小部分，化石能源仍然占主导地位——煤炭和石油各占30%，天然气占25%。

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"This is data under primary energy sources of all the countries.

VOA: standard.2010.08.03

Bioenergy is also a crucial element in the country's energy sector, supplying almost 20% of total primary energy consumption.

BBC: Finland's parliament approves two new nuclear reactors

Russia is Europe's primary energy supplier, and the new pipeline is likely to increase that dependence.

BBC: Nord Stream gas pipeline opened by Merkel and Medvedev

There is, in short, nothing new under the sun in the physics of primary energy sources.

FORBES: The Efficacy Of Presidential Energy Policy